ZnGeP2 synthesis and growth from melt

Intermediates and transport phenomena in two‐temperature synthesis of ZnGeP2

“…According to Verozubova, the Zn transport does not occur when the hot zone temperature is 1010 °C and the cold zone temperature is 520 °C [13,14]. The corresponding vapor pressure at these temperatures above pure P is ~10.5 atm (520 °C) and above pure Zn is ~2.5 atm (1010 °C).…”

“…The heat of reaction of ZnP 2 formation can be easily removed in the temperature gradient region. It can be suggested that a synthesis furnace used in [12][13][14] had better thermal isolation in the temperature gradient region, what prevented a formation of ZnP 2 during synthesis. Since vapor Zn, transported into the temperature gradient region reacted with vapor P, forming ZnP 2 , there was no undesirable remaining phosphorus in the ampoule and no explosion occurred in the following steps of the synthesis process.…”

“…The solid ZnGeP 2 resulted in nonhomogeneous material in the hot zone and reduced the rate of chemical reactions. We can suggest that in papers [12][13][14] an additional mixing of the hot zone contents was applied to remove the solid reaction products, formed on the surface of the melt to increase the reaction rate, but such procedure was not used in our case. To solve this problem the temperature of the hot zone was adjusted to 1040 °C (the saturated vapor pressure above pure Zn is ~3 atm), which was higher than the melting point of ZnGeP 2 (1027 °C).…”

“…Initially we tried to use a temperature scheme given in papers [12][13][14]. However, we found it was not fit for our situation completely.…”

“…Many works were performed to find an appropriate synthesis technique and several successes were achieved. Verozubova used two-temperature technique [12][13][14] and Schunemann used onetemperature process for synthesis of ZnGeP 2 [15,16]. Two-temperature technique seems to be high efficient, safe and can be used to synthesize a big amount of ZnGeP 2 , but there were still some problems, including the high vapor pressure of phosphorus in the synthesis process, the transport of volatile components and the complexity of the intermediates, taking place in ZnGeP 2 formation.…”