"Nanocomposites and nanomaterials"

Study of the precursors structure for preparation of nanopowders with the perovskite type phase
Shyrokov O.V., Chudinovych O.V., Lobunets T.F., Ragulya A.V.
Frantsevich Institute for Problems of Materials Science, NAS of Ukraine. Krzhizhanovsky Str., 3, Kyiv-03142, Ukraine.
E-mail: shyrokovav@gmail.com

The development of powder nanotechnologies for the creation of transparent functional ceramics is one of the promising areas of modern materials science. The interest in optical ceramics as laser, scintillation media is due to the high optical transparency in a wide range of wavelengths, high thermal conductivity, and good thermomechanical properties, chemical and thermal stability [1].
To obtain nanopowders of complex oxide phases LnLn'O3 (Ln, Ln' = REE) with the perovskite type structure, precursors were synthesized by heterogeneous precipitation from nitrate solutions of rare-earth elements in ammonia solution with urea percentage from 5 to 20 vol. % and at different temperatures.
The study of phase composition and porous structure of the obtained precursor samples was conducted by X-ray diffraction and adsorption-structural method.
Phase analysis of X-ray spectra of the studied precursor powders showed that in the angular range of 2θ = 25-35° and 40-65° a halo is observed, which indicates the amorphous nature of the samples. Also, sample No. 3 (see table) exhibits clear lines characteristic of lanthanum hydroxide.

Table – General characteristics of the porosity of synthesized samples

No.	Synthesis conditions	VΣ,
cm3/г	BET	BJH	
	vol. %	°C		SBET, m2/g	Davg.BET, nm	Vme, cm3/g	Sme, m2/g	Davg.me, nm	
1	10	40	0,0187	14,01	5,3	0,0175	13,1583	5,3	
2	10	60	0,0153	9,72	6,3	0,0132	9,5900	5,5	
3	10	80	0,0500	23,70	8,4	0,0499	33,4176	6,0	
4	5	80	0,1530	107,13	5,7	0,1573	140,1462	4,5	
5	20	80	0,2458	121,55	8,1	0,2486	173,7280	5,7	

1.	Akiyama J., Sato Y. and Taira T. New Generation of Laser Ceramics with Anisotropic Materials // Advanced Solid-State Photonics, OSA Technical Digest Series (CD) (Optical Society of America, 2009), paper MF1.