Universal approach for nonstoichiometry determination in binary chemical compounds

Abstract

A universal approach for a development of a nonstoichiometry (NS) measurement technique for binary compounds has been proposed. The approach is based on a pi‐T‐x diagram analysis for binary chemical compounds with different mutual arrangements of stoichiometry line, congruent sublimation line and SLV area. NS detection limits for PbTe, CdS, CdSe, CdTe, ZnSe, ZnTe from 10−4 up to 5 × 10−6 mol.% with a relative accuracy <18 rel.% were found out for the different excess component.

Non-stoichiometry of tris(8-hydroxyquinoline) aluminium: is it possible?

“…This is an ordinary situation which is a real challenge for modern analytical chemistry when the deviation from stoichiometry is less than 10 −2 mol%. 25 All decay kinetics of PL (at 504-508 nm) for Alq 3 crystals grown under different P 8-Hq (Fig. 7, insertion) were successfully described by two exponents (see ESI †) and the processing result is presented in Table 5.…”

Homogeneity limits and nonstoichiometry of vapor grown ZnTe and CdTe crystals

“…CdTe and ZnTe homogeneity regions were examined by a high-temperature equilibrium S ZnTeIJCdTe) LV freezing technique. 8 Deviations from the stoichiometric compositions of the quenched samples were determined using the "extraction" (direct physicochemical) method 9 based on the evaporation of an excess component of the analyzed preparation at a controlled temperature (T exctraction ) from the "hot" zone of the evacuated ampoule (Fig. 1a), a vapor violation to the "cold" zone of the ampoule, and a vapor condensation on the ampoule walls at T condensation < T extraction .…”

“…In case of ZnTe the ratio IJX impurity /X nonstoich ) varied within 1.5-2 and for CdTe it was 3-5. The measured crystal's resistivity was >10 9 Om cm and it means that in the case of the CdTe and ZnTe crystals grown from vapor by the Markov-Davydov technique, the crystal purity is a more important characteristic than nonstoichiometry, contrary to the melt grown crystals. 25…”

“…ZnTe and CdTe single crystals were grown from vapor the by the Markov-Davydov technique 7 (Fig. 6) without the contact of a growing crystal with the reactor walls (4), by the sublimation of a polycrystalline ingot (5) from a crucible (6) towards a seed (8) placed on a sapphire pedestal (9), while a part of the source material slipped into the low-temperature zone of the reactor (10) below the pedestal.…”

Investigations of Nanoscale Defects in Crystalline and Powder ZnSe Doped With Fe for Laser Application

“…The study of Fe solubility in polycrystalline ZnSe powder preparations included three stages: 1) annealing ZnSe preparations in FeSe vapor, 2) analyzing the iron concentration by ICP‐MS technique (NexION 300D, Perkin Elmer Inc, USA), 3) determination of the deviation from stoichiometry in the ZnSe preparations using the “extraction“ method described in detail in Ref. . As a starting material we used polycrystalline ZnSe, preliminary purified by re‐sublimation in dynamic vacuum.…”