The evaporation of K(dpm) = K(thd) was studied in detail by Onoe et al. [[i]] The authors found that melting and re-solidifying of precursor allowed to get a higher concentration gas containing a powder-like precursor, what allowed to obtain a high-quality KNbO3 films.
[i] A. Onoe, Y. Tasaki, K. Chikuma, J. Cryst. Growth, 2005, 277 (1-4), 546-554
Volatile potassium 2,2,6,6-tetramethylheptane-3,5-dionate K(thd) was synthesized, and the 50:50 mixture of the K(thd) and Nb(thd)4 powders was used as MO source
for the growth of 200nm KNbO3 films on c-plane sapphire at 500°C by solid source MOCVD. The deposited film was not entirely phase pure but contained a significant amount of oriented KNbO3, according to θ-2θ XRD, indicating that solid source
MOCVD can be used for the preparation of epitaxial thin films of KNbO3 after optimization of source composition to a larger K/Nb ratio; this result also indicated lower sticking coefficient (higher vaporization kinetics) of K vs. Nb on the film surface.[i]
[i] R.Hiskes, S.A.Dicarolis, J.Fouquet, Z.Lu,R.S.Feigelson,R.K.Route, F.Leplingard, C.M.Foster, MRS Proceedings 1993 335 : 299 (12 pages), « Electro-Optic Materials by Solid Source MOCVD », DOI: http://dx.doi.org/10.1557/PROC-335-299 , https://www.osti.gov/servlets/purl/10113997
Potassium 2,2,6,6-tetramethylheptane-3,5-dionate K(thd) (or potassium dipivaloylmethanate K(DPM)), combined with Li(thd) and Nb(OEt)5, was applied
as volatile metalorganic precursor for the growth of epitaxial (K,Li)NbO3 films (KLN) on (K,Li)TaO3 (KLT) single-crystal substrates by low-pressure MOCVD. XRD was used to evaluate the crystallinity of the layers; the
achievement of good epitaxial growth was confirmed by reciprocal space mapping, layer refractive indices were determined. The smoothness of (K,Li)NbO3 layer surface was smooth enough for its application as waveguide; prism coupler method revealed several guided
modes both for TE and TM waves. The cut-back method was used for estimation of the propagation loss (0.5 dB/cm at a wavelength of 633 nm).[i]
[i] K. Chikuma, A. Onoe, A. Yoshida, Jap. J. App. Phys., vol. 37, Part 1, No. 10, « Waveguiding Epitaxial Potassium Lithium Niobate Single-Crystal Films Deposited by Metalorganic Chemical Vapor Deposition », https://iopscience.iop.org/article/10.1143/JJAP.37.5582/pdf
Potassium 2,2,6,6-tetramethylheptane-3,5-dionate phenantroline adduct K(thd)(phen) was synthesized and characterized
by various methods, including investigation of thermal behavior by TGA in vacuum, and mass spectrometry from Knudsen cell. K(thd)(phen) demonstrated sufficient volatility in vacuum and was applied as K precursor for the growth of KNbO3 films by MOCVD.[i]
[i] D. Tsymbarenko, I. Korsakov, A. Mankevich, G. Girichev, E. Pelevina, A. Kaul, ECS Trans., 2009, vol.25, Iss.8, 633-638, doi: 10.1149/1.3207650, http://ecst.ecsdl.org/content/25/8/633.short, « New Complexes of Alkali-Metals as Precursors for MOCVD of Ferroelectric (K, Na)NbO3 Thin Films