Abstract

For the first time, the thermal behavior of a new mineral belomarinaite KNaSO₄ from volcanic exhalations (trigonal crystal system, Sp. gr. P3m1, a = 5.6072(3), c = 7.1781(4) Å, V = 195.45(2) ų) was studied on a natural sublimate sample from the 2012–2013 Tolbachik Fissure Eruption and its synthetic analogue, a low temperature (LT) polymorph of (Sp. gr. P3m1) in the range 30–800°C (high-temperature X‑ray diffraction) and 30–1000°C (DSC and TG). The mineral is stable up to a temperature of 470 ± 5°C, at which it has a polymorphic transformation into a high-temperature (HT) hexagonal polymorphic modification (Sp. gr. P6₃/mmc), which is stable until melted at 840°C based on DSC. The thermal expansion of both modifications is sharply anisotropic, and in the case of the HT phase the parameter a has a U-shape dependence with a minimum at T = 620°C. The volumetric expansion of the α_V HT phase is greater than that for the LT phase by factors of 2–2.5 on average.

中文翻译：

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新型矿物坡铁锰矿KNaSO 4的热学研究

摘要

对于第一次，一个新的矿物belomarinaite KNaSO的热行为₄从火山呼气（三方晶系，SP。GR。P 3米1，一个= 5.6072（3），C ^ = 7.1781（4），V = 195.45 （2）³）进行了研究从2012 - 2013年扎尔巴奇克火山喷发裂缝和它的合成类似物，的（SP。克。一个低温（LT）多晶型物的自然升华样品P 3米1）在30–800°C（高温X射线衍射）和30–1000°C（DSC和TG）的范围内。矿物是稳定达到470±5℃，在其中具有多晶型转变为高温（HT）六边形多态变形例的温度（比重= P 6 ₃ / MMC），其是稳定的，直到熔化根据DSC在840°C下。两种变体的热膨胀都具有明显的各向异性，在HT相的情况下，参数a具有U形依赖性，在T = 620°C时最小值。该α的体积膨胀_V HT相比用于通过2-2.5平均因素LT相越大。