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Chemical durability of polyphosphate glass in different medium
No full textProces rastvaranja stakla je veoma kompleksan fenomen, koji zavisi od više faktora:
sastava stakla, postupka njegovog dobijanja, površine stakla, temperature, pH rastvarača,
brzine protoka rastvarača, vremena dejstva i dr. Ovaj proces se odvija u više faza, te je
moguće kontrolisati ukupno vreme procesa, favorizovanjem ili suzbijanjem neke od ovih faza.
Iako fosfatna stakla imaju odlične optičke osobine, njihova šira primena je bila ograničena
zbog njihove niske hemijske postojanosti. Poslednjih godina, fosfatna stakla su privukla
pažnju istraživača zbog toga što poseduju bioaktivnost i biokompatibilnost, što ih svrstava u
red materijala pogodnih za primenu u medicini, stomatologiji i poljoprivredi. Upravo zbog
toga je veoma značajno da se poznaje ponašanje ovih stakala pri procesu rastvaranja u
različitim rastvaračima.
Hemijska aktivnost fosfatnih stakala u procesima koji nastaju pri kontaktu sa raznim
rastvorima pomaže pri dizajniranju i proizvodnji novih materijala. Dosadašnja istraživanja u
oblasti hemijske postojanosti neorganskih stakala su pokazala da i manje postojana stakla
mogu da budu od velike koristi u slučaju njihove kontrolisane rastvorljivosti. Glavna prednost
stakala je što im se lako može promeniti hemijski sastav. Promenom sastava, odnosno
uvođenjem novih komponenti u sastav stakla, moguće je kontrolisati kinetiku i mehanizam
rastvaranja.
U ovoj doktorskoj disertaciji prikazani su rezultati proučavanja fenomena rastvaranja
polifosfatnog stakla sastava: 45 P2O5·3 SiO2·25 K2O·15 CaO·10 MgO·1 ZnO·1 MnO u
dejonizovanoj vodi, 2 % rastvoru limunske kiseline i simuliranoj telesnoj tečnosti (SBF) u
temperaturnom intervalu 15-50 C za vremena 0,5-720 h. Ispitivanja su izvršena pri
stacionarnim uslovima u nezasićenim rastvorima. U ispitivanjima su korišćene dve grupe
praškastih uzoraka granulacija: 0,1-0,3 i 0,3-0,65 mm i kompaktni uzorci stakla.
Za analizu rezultata eksperimenata korišćene su metode: atomska apsorpciona
spektroskopija (AAS), spektrofotometrijska metoda (SF), infracrvena spektroskopija (FTIR),
diferencijalno-termijska analiza (DTA), skenirajuća elektronska mikroskopija (SEM),
energetska disperziona spektroskopija (EDS), analiza specifične površine staklenog praha i
određivanje pH vrednosti sredine.
Analizirani su: hemijski sastav, struktura i značajne fizičke osobine izabranog stakla,
promene mase uzoraka sa vremenom i temperaturom, promene koncentracija jona u
rastvorima sa vremenom i temperaturom, promene pH rastvora sa vremenom i temperaturom i
promene morfologije i sastava površinskih slojeva uzoraka sa vremenom i temperaturom pri
eksperimentima rastvaranja uzorka u dejonizovanoj vodi, 2% rastvoru limunske kiseline i
simuliranoj telesnoj tečnosti (SBF).
Zavisnosi normalizovanog smanjenja mase stakla usled rastvaranja i normalizovane
koncentracije jona u rastvorima od vremena kod svakog uzorka u sva tri rastvarača pokazuju
tri uočljive faze. Pri kratkim vremenima uočavaju se linearne (najveće) promene
normalizovanih koncentracija sa vremenom - "početna" faza. Naredna faza je "prelazna" faza
u kojoj promene normalizovanih koncentracija opadaju sa vremenom, a takođe i brzina
rastvaranja stakla. U trećoj - "krajnjoj" fazi, promene normalizovanih koncentracija su takođe
linearne i male a brzine rastvaranja su nekoliko desetina puta manje od početne brzine.
Proces rastvaranja počinje formiranjem rupa na površini uzorka. Pri porastu
temperature i vremena formira se saćasta struktura. Dalje se proces odvija formiranjem belog
sloja na površini uzorka. Debljina ovog sloja raste tokom vremena, kako proces rastvaranja
napreduje. Na uzorcima rastvaranim u dejonizovanoj vodi i SBF-u uočava se veća gustina
rupa i otvora u saćima u odnosu na uzorke rastvarane u 2% rastvoru limunske kiseline.
Takođe, stepen pokrivenosti površine kao i debljina belog sloja su primentno veći kod
uzoraka rastvaranih u dejonizovanoj vodi i SBF-u.
Uticaj temperature na koncentracije jona pri rastvaranju u sva tri rastvarača, uočava se
kao suženje "početne" i "prelazne" faze dok se "krajnja" faza širi.
Početne brzine rastvaranja u dejonizovanoj vodi kreću se od 0,063-2,55 gm-2h-1, u 2%
rastvoru limunske kiseline 2,03-28,78 gm-2h-1 i u SBF od 0,32-0,84 gm-2h-1. Vrednosti
energija aktivacije difuzije katjona u dejonizovanoj vodi kreću se u intervalu 60-130 kJmol-1,
a u 2 % rastvoru limunske kiseline u intervalu 31-76 kJmol-1.
U "prelaznoj" fazi uočava se naglo smanjenje brzine gubitka mase i brzine otpuštanja
jona u odnosu na početne brzine. Smanjenje brzine zavisi od temperature i veće je pri višim
temperaturama. Pri rastvaranju u dejonizovanoj vodi brzina rastvaranja se smanjuje od 2 do
10 puta, u 2 % rastvoru limunske kiseline od 4 do 20 puta i u SBF od 4 do 10 puta
"Krajnju" fazu rastvaranja karakteriše sporo smanjenje brzine rastvaranja. Dominantan
mehanizam koji deluje u ovoj fazi je hidroliza mreže stakla. Brzine otpuštanja jona u
"krajnjoj" fazi su u dejonizovanoj vodi u intervalu 5,08*10-4-6,57*10-2 gm-2h-1, u 2 % rastvoru
limunske kiseline u intervalu 1,06*10-3-6,92*10-2 gm-2h-1 i u SBF 8,74*10-4-7,44*10-3 gm-2h-1.
Vrednosti energija aktivacija otpuštanja jona u "krajnjoj" fazi procesa rastvaranja u
dejonizovanoj vodi su u intervalu 41-66 kJmol-1, a u 2 % rastvoru limunske kiseline u
intervalu od 42-85 kJmol-1.The dissolution of the glass is a complex phenomenon that depends upon numerous
parameters, such as glass composition, glass preparation procedure, surface condition,
temperature, pH of the solution, leaching solution volume, flow rate, exposing time of the
glass to the solution, etc. The process occurs in several steps. It allows the regulation of total
dissolution time through the favoring or suppressing some of these steps.
Although phosphate glasses have excellent optical properties, their wider application
is restricted because of poor chemical durability. In recent years, the remarkable bioactivity
and compatibility of phosphate glasses have attracted attention due to their potential
application in medicine, dentistry and agriculture. Therefore, detailed knowledge of the
dissolution behavior of phosphate glasses in different solutions is very important.
Different chemical activity of phosphate glasses, during the contact with different
solutions, provides for the opportunity to design and manufacture new materials. Previous
studies in the field of chemical durability of inorganic glass show that even less durable
glasses can be of great importance if their dissolution process is controlled.
The main advantage of glasses is their flexible behavior in response to changes of the
chemical composition. This allows the controlling of the kinetics as well as mechanism of
dissolution of glass through the introduction of new components in different amount.
The subject of this thesis is the dissolution behavior of polyphosphate glass of
composition 45 P2O5·3 SiO2·25 K2O·15 CaO·10 MgO·1 ZnO·1 MnO in deionized water, 2 %
solution of citric acid and simulated body fluid (SBF) at the temperature interval of 15-50 C
for time 0.5-720 h. The dissolution experiments were conducted under static conditions in the
unsaturated solution. Two glass powder samples, granulation 0.1-0.3 and 0.3-0.65 mm, and
the bulk glass samples, were investigated.
The methods employed for investigation were: atomic absorption spectroscopy (AAS),
spectrophotometry (SF), infrared spectroscopy (FTIR), differential thermal analysis (DTA),
scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), analysis of
specific surface areas and pH measurements.
The experiments on sample dissolution in the deionized water, 2 % solution of citric
acid and simulated body fluid (SBF) provided analysis of the chemical composition, structure
and physical properties of the parent glass. The changes in ions concentration in the solution
during time and with temperature, changes in pH measurements during time and with
temperature, and changes in morphology and composition of surface layers in the samples
during time and with temperature were determined in those experiments.
Dependence of the normalized mass release and the normalized ions concentration in
the solution on dissolution time in each solvents showed three phases. For shorter dissolution
times, the normalized ions concentration values showed the linear (largest) changes, this
phase is a so-called "initial" stage. The "initial" stage is followed by a "transitional" stage.
The trend of changes in the value of normalized concentration indicates a significant decrease
in the dissolution rate in the "transitional" stage. In the third stage, named "final", linear
dependence of normalized concentration can be observed, but changes are small.
The dissolution process starts with the formation of pits in the surface area of a sample.
For prolonged treatment, the honeycomb-like structure covers the whole surface of the glass.
The white layer can be observed on the surface. Thickness of this layer grows over time, as
the dissolution process continues. The samples tested in the deionized water and SBF show
bigger density of pits and holes in the honeycomb-like structure, compared to the samples
treated in 2 % solution of citric acid. Also, the extent of covered surface, as well as the
thickness of white layer, are notably bigger with the samples treated in the deionized water
and SBF.
The temperature impact on concentration of the dissolved ions during dissolution in all
three solvents is observed as narrowing of the "initial" and "transitional" stage, while the
"final" stage is expanding.
The initial dissolution rates in deionized water start from 0.063-2.55 gm-2h-1; in 2%
solution of citric acid from 2.03-28.78 gm-2h-1 and in SBF from 0.32-0.84 gm-2h-1. The anion
diffusion activation energy values in the deionized water vary within the interval of 60-130,
while in the 2 % solution of citric acid vary within the interval of 31-76 kJ/mol.
The sudden decrease in dissolution rate and ions release rate is noted in the
"transitional" stage. The dissolution rate decreases 2 to 10 times during dissolution in the
deionized water, 4-20 times in the 2 % solution of citric acid and 4-10 times in the SBF.
The slow decrease in dissolution rate characterizes "final" dissolution stage. The glass
matrix hydrolysis is a dominant mechanism in this stage. The ions release rates in the
deionized water are in the 5.08*10-4-6.57*10-2 gm-2h-1 interval; in the 2 % solution of citric
acid in the 1,06*10-3-6,92*10-2 gm-2h-1 interval, while in the SBF 8,74*10-4-7,44*10-3 gm-2h-1.
The values of the ion diffusion activation energy in the final stage of dissolution process in
the deionized water are in the 41-66 kJmol-1 interval, while in the 2 % solution of citric acid
are in the 42-85 kJmol-1 interval
Potencijal hidročađi komine grožđa za uklanjanje odabranih teških metala iz vodenih rastvora
No full textU okviru ovog rada hidročađ komine grožđa je ispitana kao potencijalni adsorbens
jona olova i bakra iz vodenih rastvora. U cilju poboljšanja adsorpcionog kapaciteta dobijena
hidročađ je alkalno modifikovana rastvorom kalijum-hidroksida. Eksperiment je vršen u
šaržnom sistemu pri različitim koncentracijama jona metala u rastvoru. Adsorpcioni testovi
su pokazali da se pri koncentraciji jona metala od 0,5 mmol/L uspostavlja ravnoteža u sistemu
i da modifikovana hidročađ pokazuje skoro pet puta bolji adsorpcioni kapacitet u odnosu na
nemodifikovanu za oba ispitivana jona. Dobijeni rezultati pokazuju da se alkalno modifikovana
hidročađ komine grožđa može efikasno koristiti kao adsorbens jona metala iz vodenih
rastvora
The extraction of aggregates in Serbia, 1973-2015-a statistical exploration
No full textWe contribute to the fields of mineral economics, environmental and economic history in two respects: first, we construct a novel time series data set for the levels of aggregates extraction in Serbia
between 1973 and 2015; the second, we estimate a change point ordinary least squares regression to
model the dynamics of aggregates extraction in the aforementioned period. Our cliometric estimates are
in great accordance with the major business cycle facts of the Serbian economy in the last 40 years. The
most important policy implication of our results pertains to the potential slowdown of aggregates ex-
traction from the onset of the Great Recession
In Situ Synthesis of Biocompatible Composite Layer of Hydroxyapatite/Passive Oxide Surfaces on the Modified Titanium
No full textHydroxyapatite (HAp) is the most suitable biocompatible material for bone implant coatings.
However, its brittleness is a major obstacle, and that is why, recently, research focused on creating composites.
In this study, a novel in situ synthesis of HAp coating on titanium was presented. HAp was anaphoretically
deposited from alkaline-ethanol suspension in one step process. Morphology of the coating was investigated by
optical microscopy, while deposited HAp was characterized using ATR-FTIR. It was concluded that HAp has
excellent coverage of the surface without delamination. The obtained coating can be good material for bone
implants due to solving HAp brittleness
Mineralogy and genetic features of the Cu-As-Ni-Sb-Pb mineralization from the Mlakva polymetallic deposit (Serbia) - New occurrence of (Ni-Sb)-bearing Cu-arsenides
No full text(Ni-Sb)-bearing Cu-arsenides are rare minerals within the Mlakva and Kram mining sectors (Boranja ore field) one of the less-known Serbian Cu deposits. (Ni-Sb)-bearing Cu-arsenides were collected from the Mlakva skarn-replacement Cu(Ag,Bi)-FeS polymetallic deposit. The identified phases include/3-domeykite, Ni-bearing koutekite and (Ni-Sb)-bearing alpha-domeykite. (Ni-Sb)-bearing Cu-arsenides are associated with nickeline, arsenical breithauptite, chalcocite, native Ag, native Pb and litharge. Pyrrhotite, pyrite, chalcopyrite, cubanite, bismuthinite, molybdenite, sphalerite, galena, Pb(Cu)-Bi sulfosalts and native Bi, as well as minor magnetite, scheelite and powellite are associated with the sulfide paragenesis. The electron microprobe analyses of the (Ni-Sb)-bearing Cu-arsenides yielded the following average formulae: (Cu-2.73,Ni-0.17,Fe-0.03,Ag-0.01)(Sigma 2.94)(-AS(0.98)Sb(0.05)S(0.02))(Sigma) (1.06-)beta-domeykite (simplified formula ( CU2.7,Ni-0,Ni-2)(Sigma 2.9)AS(1.1)); (Cu-3.40,Ni-1.40,Fe-0.11)(Sigma 4.91)(-AS(1.94)Sb(0.13)S(0.02))(Sigma 2.08)-Ni-bearing koutekite (simplified formula (Cu3.4Ni1.5)Sigma As-4.9(2.1)); and Cu-1.97(Ni-0.98,Fe-0.03)Sigma(1.01)(As-0.81,Sb-0.22)Sigma(1.03)-(Ni-Sb)-bearing alpha-domeykite (simplified formula Cu2NiAs). The Rietveld refinement yielded the following unit-cell parameters for beta-domeyldte and Ni-bearing koutekite: a = 7.1331(4); c = 7.3042(5) A; V = 321.86(2) A(3), and a = 5.922(4); b = 11.447(9); c = 5.480(4) A; V = 371.48(5) A(3), respectively. Ore geology, paragenetic assemblages and genesis of the Mlakva deposit are discussed in detail and the Cu-As-Ni-Sb-Pb mineralization has been compared with similar well-known global deposits
Ionically cross-linked chitosan-halloysite composite microparticles for sustained drug release
No full textThis study investigated the potential of halloysite nanotubes (HNTs) to improve the sustained release properties of chitosan (CS) microparticles cross-linked ionically with tripolyphosphate (TPP). Composite CS-HNTs microparticles were obtained by a simple and eco-friendly procedure based on a coaxial extrusion technique. Prior to encapsulation, a water-soluble model drug, verapamil hydrochloride (VH), was adsorbed successfully on HNTs. The microparticles were characterized by optical microscopy, Fourier transform infrared (FTIR) spectroscopy, differential thermal analysis/thermogravimetric analysis (DTA/TG) and evaluated for encapsulation efficiency and drug-release properties. The composite particles had a slightly deformed spherical shape and micrometric size with average perimeters ranging from 485.4 +/- 13.3 to 492.4 +/- 11.9 mu m. The results of FTIR spectroscopy confirmed non-covalent interactions between CS and HNTs within composite particle structures. The DTA and TG studies revealed increased thermal stability of the composite particles in comparison to the CS-TPP particles. Drug adsorption on HNTs prior to encapsulation led to an increase in encapsulation efficiency from 19.6 +/- 2.9 to 84.3 +/- 1.9%. In contrast to the rapid release of encapsulated model drug from CS-TPP microparticles, the composite CS-HNTs microparticles released drug in a sustained manner, showing the best fit to the Bhaskar model. The results presented here imply that HNTs could be used to improve morphology, encapsulation efficiency and sustained drug-release properties of CS microparticles cross-linked ionically with TPP
The efficacy of raw and concentrated bentonite clay in reducing the toxic effects of aflatoxin in broiler chicks
No full textThe objective of this study was to evaluate the efficacy of two adsorbents, a raw bentonite clay (RC) and a concentrated bentonite clay (CC), in ameliorating the toxic effects of aflatoxin B1 (AFB1). Results of the in vitro study (pH 3.0) indicated the CC adsorbed more AFB1 than RC (93.39 mg/g vs. 79.30 mg/g) suggesting that CC may be more effective than RC in reducing the toxic effects of AFB1. One hundred and eighty day-old straight run broiler chicks were assigned to 6 replicate pens of 5 chicks each and assigned to 6 dietary treatments from hatch to day 21. Dietary treatments included: 1) basal diet (BD) containing no AFB1 or adsorbents; 2) BD plus 0.50% RC; 3) BD plus 0.50% CC; 4) BD plus 2.0 mg AFB1/kg; 5) BD plus 2.0 mg AFB1/kg plus 0.50% RC; and 6) BD plus 2.0 mg AFB 1/kg plus 0.50% CC. Dietary AFB1 concentrations were confirmed by analysis and diets were screened for other mycotoxins prior to the start of the experiment. The addition of AFB1 to the feed reduced (P LT 0.05) growth performance and increased (P LT 0.05) relative liver weight (RLW) and kidney weight (RKW) of chicks fed AFB1 compared to control chicks on day 21. These changes were ameliorated (P LT 0.05) by the addition of RC and CC to the AFB1 diet. Mild to moderate lesions of aflatoxicosis (2.25) were observed in chicks fed AFB1 alone on day 21. The addition of both RC and CC to the AFB1 diet decreased (P LT 0.05) but did not prevent liver lesions (0.92 and 1.42, respectively). Results indicate that both RC and CC were effective in reducing the toxic effects of AFB1, however the cost of processing of CC would make the RC a more economical product for reducing the effects of AFB1 in young broiler chicks
The Crystal Structure of the Ba-Hexacelsian Phases Doped with Ca2+ and Pb2+
No full textThe ion-exchange procedure is used for doping the Ba-hexacelsian structure with Ca2+ and Pb2+ cations. The hexacelsian doped with Ca2+ has a composition of Ba0.64Ca0.36Al2Si2O8, and hexacelsian doped with Pb2+ has a composition Ba0.9Pb0.1Al2Si2O8. The crystal structure of both doped hexacelsians was refined by Rietveld refinement procedure. The crystal structure of Ca-hexacelsian is refined in the space group P (3) over bar c1, and results indicate ordering distribution of Si and Al (unit cell parameters is a = 5.2995, c = 15.594 angstrom and agreement factors: R-exp = 15.3 R-p = 19.9, R-wp = 19.0, R-B = 15.0 R-F = 4.08). Structural model for Pb-hexacelsian samples is described in the space group P6(3)/mcm with disorder distribution Si/Al (unit cell parameter is a = 5.2973, c = 15.591 angstrom and agreement factors R-exp = 21.5 R-p = 21.5, R-wp = 19.0, R-B = 5.74 R-F = 4.08). The results of Rietveld refinements indicate that Ca2+ and Pb2+ cations are incorporated into hexacelsian structure in different position
Mechanism of polymetallic concentrate leaching with sulfuric acid and hydrogen peroxide solution
No full textThe determination of mechanism of the polymetallic concentrate leaching with sulfuric
acid and hydrogen peroxide was done based on the characterization of the starting
concentrate and leach residues. The application of XRD and thermal analysis on the
leaching mechanism determination was done. The phase content of concentrate and leach
residues were determined by X-ray analysis using diffractometer PHILIPS PW-1710. DTA
and TG analysis were performed in air atmosphere up to 1173 K on NETZSH, model 409
EP, device.
The polymetallic concentrate, used in experiments, has the following chemical
composition (in wt. %): Cu-8.92, Zn-8.79; Pb-12.66, Fe-19.80 and S-21.4. X-ray phase
analysis of the concentrate reveals that the sample contains chalcopyrite, sphalerite, galena
pyrhotite and quartz (Fig. a). On Fig. b the DTA and TG curves of polymetallic concentrate
are shown. Curves include two parts: first, a low temperature, which correspond to the
sulfides oxidation (the mass increase on the TG, and exothermic peaks on the DTA); and
second which correspond to the dissociation of sulphates and oxysulphates (the mass loss
on the TG, and endothermic peaks on the DTA).
The phases identified in the leach residue by XRD were elemental sulphur, anglesite,
chalcopyrite, sphalerite, galena pyrhotite and quartz (Fig. c), which confirms that the
elemental sulphur is formed during leaching. In Fig. d the TG-DTA curve of the leach
residue are shown. On DTA curve on the temperature of 118 oC, the endothermic peak as a
result of elemental sulfur melting is clearly visible. Then, in the range of 250-350 oC,
weight loss as a consequence of the oxidation of sulfur to SO2 gas occurs. The loss of mass
due to combustion of sulfur on Fig. d is smaller than the sulfide sulfur which is oxidized
during the leaching process, which indicates that the sulfur from sulfides is oxidised both
to the sulfate and to the elemental form. The mass increase followed by exothermic effects
in the range of 400-700 oC is a result of the oxidation of unleached sulphides in the solid
residues. At temperatures above 720 °C weight loss occurs as a result of dissociation of
sulphate and oxysulphates of lead, zinc, copper and iron with endothermic peaks on the
DTA curve. XRD and DTA/TG studies have contributed in determining the mechanism of
polymetallic concentrate leaching process in the system H2SO4-H2O2-H2O:CuFeS2 + 5/2H2O2 + 5/2H2SO4 = CuSO4 + 1/2Fe2(SO4)3 + 2S0 + 5H2O
(1)
CuFeS2 + 17/2H2O2 + 1/2H2SO4 = CuSO4 + 1/2Fe2(SO4)3 + 9H2O(2)
ZnS + H2O2 + H2SO4 = ZnSO4 + S0 + 2H2O (3)
ZnS + 4H2O2 = ZnSO4 + 4H2O (4)
PbS + H2O2 + H2SO4 = PbSO4 + S0 + 2H2O (5)
PbS + 4H2O2 = PbSO4 + 4H2O (6
Kristalna struktura Mn-anortita sintetisanog iz zeolita jonskom izmenom sa LTA i FAU topologijom
No full textThe most common zeolites which are used as precursors for ceramic materials are synthetic zeolites of LTA, FAU or GIS topology. Eberhard presented the first data for synthetic feldspars MnAl2Si2O8 [1], while Matsui and Kimata presented the structural
results of investigation in the three component system MnAl2Si2O8−CaAl2Si2O8−SrAl2Si2O8 [2].
Thermally induced phase transformation of Mn-exchange LTA and FAU zeolites are followed in the range from room temperature to 1300 ºC. Both frameworks collapse into amorphous intermediate products after heating between 600 and 650 °C. Prolonged heating of the intermediate product over 1100°C results directly in formation of a
disorder Mn anorthite LTA [a = 8.10 95(4) Å, b = 12.824(4) Å, c = 7.0674(4) Å, β = 115.89(3)] and Mn anorthite FAU [a = 8.0498(4) Å, b = 12.758(4) Å, c = 7.0356(4) Å, β =116.13(3)] phase. The phase conversions in the temperature range investigated were followed by thermal (DTA, TGA, and DSC) and FTIR analyses. The crystal structures of both anorthite phases are refined by Rietveld method against X- ray powder diffraction data (Figure 1).Najčešći zeoliti koji se koriste kao prekursori za keramičke materijale su sintetički zeoliti sa LTA, FAU ili GIS topologijom. Eberhard je prvi publikovao strukturne
podatke za sintetičke feldspate, sa formulom MnAl2Si2O8 [1], dok su Matsui i Kimata
prvi predstavili strukturne podatke za trokomponentni sistem, sa bruto formulom
MnAl2Si2O8−CaAl2Si2O8−SrAl2Si2O8 [2].
Termički indukovane fazne transformacije LTA i FAU zeolita sa izmenjenim Mn, praćene su u opsegu temperatura od sobne do 1300 ºC. Kolaps u amorfnim intermedijerima kod oba tipa zeolita se javlja nakon zagrevanja između 600 i 650 °C. Produženo zagrevanje intermedijernog proizvoda preko 1100 °C rezultatira direktnom
formiranju disordera
u Mn-anortit-LTA
[a = 8.1095(4) Å, b
=
12.824(4)
Å,
c = 7.0674(4) Å,
β
=
115.89(3)]
i
Mn-anortit-FAU fazi
[a
=
8.0498(4)
Å,
b = 12.758(4) Å,
c
= 7.0356(4) Å,
β
=
116.13(3)]. Fazni
prelazi
u ispitivanom
temperaturnom opsegu praćena je primenom termalne (DTA, TGA i DSC) i FTIR analize. Kristalne strukture oba anortita su utačnjene korišćenjem Ritveldove metode (slika 1), primenjene na podatke prikupljene rendgenskom difrakcijom sa polikristalnih materijala