Короткохвильова люмінесценція подвійних фосфатів цинку / мангану Zn2-xMnxP2O7•nH2O (n = 0, 1, 5; х = 0 - 2)

Анотація

SHORT-WAVE LUMINESCENCE OF DOUBLE PHOSPHATES

Zn_2-xMn_xP₂O₇·nH₂O (n = 0, 1, 5; х = 0 - 2)

V. Boyko, O. Gomenyuk, S. Nedilko

Aim of researches - to investigate short-wave luminescence (range of 280 - 650 nm) of standards - diphosphates Zn_2-xMn_xP₂O₇·nH₂O without Mn (x = 0) and with Mn (x ≠ 0), both waterless (n = 0) and with different content of crystallizational water (n = 1 - 5). Such researches practically were not conducted and have not only scientific interest from position of physics of luminescent processes in such materials but also give information on the structure of hydrates of double phosphates of Zn/ Mn, that known for the practical applications. These researches are actual and perspective.

Experimental methods and equipments  for experimental researches

Luminescence of standards was investigated at T = 4,2;  77 and 300 К. Standards took place in helium or nitric refrigerators, in liquid helium or nitrogen at the temperature of standards 4,2 or 77 К accordingly. Luminescence was excited by the radiation of laser (wave-length of excitation l = 337,1 nm) and by the radiation of xenon lamp (area lengths of waves of excitation of 300 - 650 nm).

Spectrums of luminescence at excitation in the areas of a vacuum ultraviolet and spectrums excitation in this area measured at the station of SUPERLUMI to the synchrotron of DESY toHamburg(Germany). The spectrums of luminescence were written down in the range of lengths of waves of 275 - 950 nm spectrums of excitation of luminescence - in the range of 50 - 334 nm at temperatures from subzero (helium) 10 К to 300 K.

Experimental results and their discussions

In the spectrums of short-wave luminescence (range of 280 - 650 nm) of investigational diphosphates of zinc Zn_2-xMn_xP₂O₇·nH₂O without Mn (x = 0) and with Mn (x ≠ 0), both waterless (n = 0) and with different content of crystallizational water (n = 1 - 5)  there is two the basic component radiations separated after a location. It is a stripe that lies in a range near 340 nm and wide stripe of blue-pink radiation are in the range of 350 - 650 nm, position of a maximum of by-pass that depends on composition Zn/Mnand from the amount of molecules of water. Our experimental data in relation to these stripes of radiation, for today, not enough, to do exact conclusions in relation to their origin. Literary data, where luminescent properties of similar connections, also avaricious enough, are described. Red luminescence that for waterless connections better became excited in the short-wave components of spectrums of excitation, for connections with water better becomes excited in long-wave, that confirms existence of the different systems of defects also.

Сonclusions

1. The brought results over allow to examine ultraviolet, so blue-pink luminescence of investigational connections, as such, that created by the defects of structure. About it testifies that addition of water results in the strong increase of intensity of long-wave components even, while short-wave part of spectrums does not almost change.

2. Red luminescence that for waterless connections better became excited in the short-wave components of spectrums of excitation confirms existence of the different systems of defects, that is created by the molecules of water, the atoms of that can be included in the nearest surroundings of bivalent metal of grate in different surroundings (both tetrahedral and in octahedral).