scholarly journals Pb1-xMnxTe single crystals and their structural properties

2004 ◽  
Vol 69 (12) ◽  
pp. 1121-1128 ◽  
Author(s):  
Aleksandar Golubovic ◽  
Slobodanka Nikolic ◽  
Stevan Djuric ◽  
Nebojsa Romcevic
Keyword(s):  
Diffraction Analysis ◽  
Single Crystals ◽  
Structural Properties ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Chemical Polishing ◽  
Published Data ◽  
Etching Solution ◽  
X Ray ◽  
Vertical Bridgman

Pb1-xMnxTe crystals were grown by the vertical Bridgman method. Their structural properties were observed both by optical microscopy after chemical polishing and ething, and by X-ray powder diffraction analysis. A solution of 5 vol. % Br2 in HBr at room temperatur, for an exposure of 2 min was determined for chemical polishing. Asolution of 20 g KOH in 1 ml H2O2, 2 ml glycerol (C3H8O3), and 20 ml H2O at room temperature for an exposure for 6 min was found to be a suitable etching solution. The obtained results are discussed and compared with published data.

scholarly journals The growth of sapphire single crystals

2001 ◽  
Vol 66 (6) ◽  
pp. 411-418 ◽  
Author(s):  
Aleksandar Golubovic ◽  
Slobodanka Nikolic ◽  
Stevan Djuric ◽  
Andreja Valcic
Keyword(s):  
Crystal Growth ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Chemical Polishing ◽  
Published Data ◽  
Czochralski Technique ◽  
Critical Rate ◽  
Etching Solution ◽  
X Ray ◽  
Crystal Diameter

Sapphire (Al2O3) single crystals were grown by the Czochralski technique both in air and argon atmospheres. The conditions for growing sapphire single crystals were calculated by using a combination of Reynolds and Grash of numbers. Acritical crystal diameter dc = 20 mm and the critical rate of rotation c = 20 rpm were calculated from the hydrodynamics of the melt. The value of the rate of crystal growth was experimentally found to be 3.5 mm/h. According to our previous experiments, it was confirmed that three hours exposures to conc. H3PO4 at 593 K was suitable for chemical polishing. Also, three hours exposure to conc.H3PO4 at 523Kwas found to be a suitable etching solution. The lattice parameters a = 0.47573 nm and c = 1.29893 nm were determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

scholarly journals The growth of Mg2TiO4 single crystals using a four-mirror furnace

2011 ◽  
Vol 76 (11) ◽  
pp. 1561-1566 ◽  
Author(s):  
Aleksandar Golubovic ◽  
Marko Radovic
Keyword(s):  
Optical Properties ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Spectroscopic Ellipsometry ◽  
Lattice Parameter ◽  
Published Data ◽  
X Ray ◽  
Float Zone

A single crystal of Mg2TiO4 was grown by the travelling solvent float zone (TSFZ) method. The lattice parameter a = 0.8444(8) nm was determined by X-ray powder diffraction analysis. The optical properties of the Mg2TiO4 single crystals were studied using spectroscopic ellipsometry. The obtained results are discussed and compared with published data.

scholarly journals The growth of ruby single crystals

2005 ◽  
Vol 70 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Aleksandar Golubovic ◽  
Slobodanka Nikolic ◽  
Stevan Djuric ◽  
Andreja Valcic
Keyword(s):  
Crystal Growth ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Argon Atmosphere ◽  
Published Data ◽  
Czochralski Technique ◽  
Critical Rate ◽  
Etching Solution ◽  
X Ray ◽  
Crystal Diameter

Ruby (Cr:Al2O3) single crystals were grown by the Czochralski technique in an argon atmosphere. The critical crystal diameter dc = 1.0 cm and the critical rate of rotation ?c = 20 rpm were calculated by equations of the hydrodynamics of the melt. The rate of crystal growth was experimentally obtained to be 2.7 mm/h. For chemical polishing, conc. H3PO4 at 593 K for an exposure of 3 hours was determined. Conc. H3PO4 at 523 K for an exposure of 3 h was found to be a suitable etching solution. The lattice parameters a = 0.47627(6) nm and c = 1.301(1) nm were determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

scholarly journals The growth of Nd:CaWO4 single crystals

2003 ◽  
Vol 68 (12) ◽  
pp. 1001-1009 ◽  
Author(s):  
Aleksandar Golubovic ◽  
Slobodanka Nikolic ◽  
Rados Gajic ◽  
Stevan Djuric ◽  
Andreja Valcic
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Chromic Acid ◽  
Critical Diameter ◽  
Published Data ◽  
Hydrodynamic Equations ◽  
Czochralski Technique ◽  
Critical Rate ◽  
X Ray ◽  
C 30

CaWO4 doped with 0.8 % at. Nd (Nd:CaWO4) single crystals were grown from the melt in air by the Czochralski technique. The critical diameter dc = 1.0 cm and the critical rate of rotation ?c = 30 rpm were calculated from hydrodynamic equations for buoyancy-driven and forced convection. The rate of crystal growth was experimentally obtained to be 6.7 mm/h. For chemical polishing, a solution of 1 part saturated chromic acid (CrO3 in water) and 3 parts conc. H3PO4 (85 %) at 433 K with an exposure time of 2 h was found to be adequate. A mixture of 1 part concentrated HF and 2 parts chromic acid at room temperature after exposure for 30 min was found to be a suitable etching solution. The lattice parameters a = 0.52404 (6) nm, c = 1.1362 (6) nm and V0 = 0.312 (2) nm3 were determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

Identification of two lead perovskites, Pb2ScTaO6 and Pb(Sc0.5Nb0.5)O3, by X-ray powder diffraction patterns

1993 ◽  
Vol 8 (3) ◽  
pp. 191-193 ◽  
Author(s):  
C. Caranoni ◽  
P. Lampin ◽  
C. Boulesteix
Keyword(s):  
Single Crystals ◽  
Powder Diffraction ◽  
Perovskite Structure ◽  
Room Temperature ◽  
Stoichiometric Mixture ◽  
High Quality ◽  
Space Group ◽  
X Ray ◽  
Diffraction Patterns ◽  
Degree Of Order

Substituting cations in materials with the formula Pb2B′B″O6 is more or less ordered on the B sites. High-quality single crystals of Pb2ScTaO6 (PST) and Pb(Sc0.5Nb0.5)O3 (PSN) were prepared from two thermal cycles. A stoichiometric mixture of the constituent oxides was prefired at up to 1000 °C, and then crystals were grown from a PbO–B2O3–PbF2 flux mixture, starting at a temperature of 1100 °C for PSN and 1200 °C for PST. At room temperature, X-ray examination showed that PSN had a perovskite structure with a cubic unit-cell and a refined parameter a = 4.080(1 ) Å, space group Pm3m and Z = 1, whereas PST formed a well-ordered superlattice with a = 8.136(1) Å, Z = 4 and space group Fm3m. In each case a fully indexed powder pattern is presented. The degree of order is estimated to be close to 80% for PST and less than 10% for PSN.

scholarly journals Growth of Antimony Selenide Crystals by Bridgman-Stockbarger Method

2009 ◽  
Vol 8 (2) ◽  
pp. 1-6
Author(s):  
Chandrasekharan K. A. ◽  
Kunjomana A. G.
Keyword(s):  
Chemical Analysis ◽  
Diffraction Analysis ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Vickers Hardness ◽  
Energy Gap ◽  
X Ray ◽  
Hardness Tester ◽  
Stockbarger Method ◽  
Antimony Selenide

Single crystals of antimony selenide were grown from melt by the Bridgman Stockbarger method. X-ray powder diffraction analysis was carried out to determine the lattice parameters of the grown samples.The morphology and chemical analysis of cleavage planes were investigated using SEM and EDAX. The microhardness studies were done by using a Vickers hardness tester. The correlation of energy gap and microhardness has also been investigated.

Notizen: Preparation and Crystal Structure of NiHg

1977 ◽  
Vol 32 (4) ◽  
pp. 479 ◽  
Author(s):  
M. Pušelj ◽  
Z. Ban
Keyword(s):  
Crystal Structure ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Single Phase ◽  
Extended Period ◽  
Structure Type ◽  
X Ray

A single phase binary amalgam of the composition NiHg was found to form at room temperature after an extended period of time (approx. 2 years).X-ray powder diffraction analysis enabled us to determine the crystal structure. The compound crystallizes tetragonally with a = 4.22 Å and c = 3.14 Å. It belongs to L 10 crystal structure type.

scholarly journals The growth of Nd: YAG single crystals

2002 ◽  
Vol 67 (4) ◽  
pp. 291-300 ◽  
Author(s):  
Aleksandar Golubovic ◽  
Slobodanka Nikolic ◽  
Rados Gajic ◽  
Stevan Djuric ◽  
Andreja Valcic
Keyword(s):  
Crystal Growth ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Lattice Parameter ◽  
Argon Atmosphere ◽  
Published Data ◽  
Czochralski Technique ◽  
Critical Rate ◽  
X Ray ◽  
Crystal Diameter

Y3Al5O12 doped with 0.8%wt.Nd (Nd:YAG) single crystals were grown by the Czochralski technique under an argon atmosphere. The conditions for growing the Nd:YAG single crystals were calculated by using a combination of Reynolds and Grashof numbers. The critical crystal diameter and the critical rate of rotation were calculated from the hydrodynamics of the melt. The crystal diameter Dc=1.5 cm remained constant during the crystal growth while the critical rate of rotation changed from ?c=38 rpm after necking to ?c=13 rpm at the end of the crystal. The value of the rate of crystal growth was experimentally found to be 0.8?1.0 mm/h. According to our previous experiments, it was confirmed that 20 min exposure to conc. H3PO4 at 603 K was suitable for chemical polishing. Also, one-hour exposure to conc. H3PO4 at 493 K was found to be suitable for etching. The lattice parameter a=1.201 (1) nm was determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

X-ray powder diffraction analysis of ±-fenoprofen calcium dihydrate

2002 ◽  
Vol 17 (3) ◽  
pp. 244-246
Author(s):  
Ailette Aguila Tobien ◽  
Peter Varlashkin
Keyword(s):  
Single Crystal ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Unit Cell ◽  
Powder Pattern ◽  
Crystal Data ◽  
Racemic Compound ◽  
Internal Standards ◽  
X Ray

The current JCPDS powder pattern for the racemic compound fenoprofen calcium dihydrate (card No. 44-1790) is unindexed. Previously we reported the single crystal data, determined at −100 °C, for this material (Zhu et al., 2001). Using 2θ values obtained from a powder pattern spiked with internal standards, we indexed the room temperature powder pattern. The resulting unit cell values for the monoclinic P21/n cell are a=19.018 Å, b=7.738 Å, c=19.472 Å, β=91.66°.

X-ray powder diffraction analysis of abacavir hemisulfate

2005 ◽  
Vol 20 (3) ◽  
pp. 241-245 ◽  
Author(s):  
Gerald Monger ◽  
Peter Varlashkin
Keyword(s):  
Reverse Transcriptase ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Internal Standard ◽  
Unit Cell ◽  
Powder Pattern ◽  
Hiv Reverse Transcriptase ◽  
X Ray ◽  
Anti Hiv

The room temperature powder pattern of abacavir hemisulfate (anti-HIV reverse transcriptase compound) was indexed using 2θ values obtained from a powder pattern spiked with an internal standard. The resulting unit cell values for the monoclinic I2 cell [nonstandard setting of C2 (No. 5)] are a=13.278(1) Å, b=8.437(1) Å, c=14.259(2) Å, β=93.87(1)°. There are two formula units [(C14H16N6O)2.H2SO4] per unit cell and Dx=1.390 g∕cm3.

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