We tried to clarify to the deposition mechanism by applying the 11B and 19F NMR analyses to the LPD reaction solutions for the preparing titanium oxide films with various reaction conditions. Moreover, the optimum conditions of the syntheses of 3d transition metal oxide thin films were investigated by con-trolling pH and the concentration of reacting species. In the reaction of TiO2 deposition, TiF62- do not re-lease all F- ions, namely, the existence of hydrolysis intermediate species (TiFx(OH)y(H2O)6-x-y(4-x-y)) which could not be detected by 19F NMR because of the rapid ligand exchange in the LPD reaction solu-tions. In the reaction of Cr2O3 deposition, the optimization of the LPD reaction can be carried out by the controlling of the concentrations of reaction species and pH.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3522

Ikuta, Hirotaka

Maki, Hideshi

Mizuhata, Minoru

Okumura, Yuzo

We tried to clarify to the deposition mechanism by applying the 11B and 19F NMR analyses to the LPD reaction solutions for the preparing titanium oxide films with various reaction conditions. Moreover, the optimum conditions of the syntheses of 3d transition metal oxide thin films were investigated by con-trolling pH and the concentration of reacting species. In the reaction of TiO2 deposition, TiF62- do not re-lease all F- ions, namely, the existence of hydrolysis intermediate species (TiFx(OH)y(H2O)6-x-y(4-x-y)) which could not be detected by 19F NMR because of the rapid ligand exchange in the LPD reaction solu-tions. In the reaction of Cr2O3 deposition, the optimization of the LPD reaction can be carried out by the controlling of the concentrations of reaction species and pH

Minoru Mizuhata

Hirotaka Ikuta

Yuzo Okumura

Hideshi Maki

CiteSeerX

Equilibrium Behavior for Transition Metal Ionic Species in Liquid Phase Deposition Reaction

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 2 No 1, 01NTF36(3pp) (2013)   2304-1862/2013/2(1)01NTF36(3) 01NTF36-1  2013 Sumy State University Equilibrium Behavior for Transition Metal Ionic Species in Liquid Phase Deposition Reaction  Minoru Mizuhata*, Hirotaka Ikuta, Yuzo Okumura, Hideshi Maki  Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe, 657-8501 Japan  (Received 10 June 2013; published online 03 September 2013)  We tried to clarify to the deposition mechanism by applying the 11B and 19F NMR analyses to the LPD reaction solutions for the preparing titanium oxide films with various reaction conditions. Moreover, the optimum conditions of the syntheses of 3d transition metal oxide thin films were investigated by con-trolling pH and the concentration of reacting species.  In the reaction of TiO2 deposition, TiF62- do not re-lease all F- ions, namely, the existence of hydrolysis intermediate species (TiFx(OH)y(H2O)6-x-y(4-x-y)) which could not be detected by 19F NMR because of the rapid ligand exchange in the LPD reaction solu-tions.  In the reaction of Cr2O3 deposition, the optimization of the LPD reaction can be carried out by the controlling of the concentrations of reaction species and pH.  Keywords: Liquid Phase Deposition, Titanium Oxide, Chromium Oxide, Transition Metal Oxide    PACS number: 73.90._f                                                             * mizuhata@kobe-u.ac.jp 1. INTRODUCTION  Metal oxide thin films have been widely applied as inorganic functional materials due to their electrical, optical, and magnetic properties. Recently, a novel wet process called Liquid Phase Deposition (LPD) method has attracted much attention. The LPD reaction spon-taneously proceeds at ambient condition in a balance of two equilibrium reactions, which are principally de-scribed as follows: the hydrolysis equilibrium (ligand-exchange) reaction of metal fluoride complex species (eq. 1) and the F– consumption reaction with boric acid or aluminum ion as an F– scavenger (eq. 2 or 3)[1].   MFx(x-2n)- + H2O ↔ MOn + xF– + 2nH+ (1)  (M; e.g. Ti, Fe, Cu, Zr, Sn, W, Mo, V, Zr, Nb, Ni)    H3BO3 + 4HF → BF4– + H3O+ + 2H2O (2)   Al3+ + 6HF → H3AlF6 + 3/2H2  (3)  Deki et al. have adapted LPD method to the fabrica-tion of various kinds of films, such as titanium oxide, vanadium oxide, iron oxy-hydroxide and multi compo-nent metal oxide films [2-4]. However, a small amount of fluorine is incorporated into the synthesized thin film and the essence of the deposition mechanism is still unclear. The clarification of the LPD reaction mechanism is indispensable to optimization, the high yield synthesis, and the physical properties improve-ment of the thin film synthesis condition. In this work, we tried to clarify to the deposition mechanism by ap-plying the 11B and 19F NMR analyses to the LPD reac-tion solutions for the preparing titanium oxide films with various reaction conditions. Moreover, the opti-mum conditions of the syntheses of 3d transition metal oxide thin films were investigated by controlling pH and the concentration of reacting species.  2. EXPERIMENTAL  The (NH4)2TiF6 concentrations of the parent solu-tions for the syntheses of TiO2 thin films  were 0.025, 0.1 and 0.2 mol L-1, and the H3BO3 concentration was fixed at 0.2 mol L-1. The degreased glass substrates were suspended vertically into the parent solution, and reacted at 30 C. The 19F NMR spectra were obtained by a Varian INOVA 400 NMR spectrometer. For the syn-theses of Cr2O3 thin films, the Cr(NO3)3 and the HF concentrations of the parent solutions were 0.05 mol L-1 and 0.15 mol L-1, respectively. The pH of the parent solutions were controlled by NH3 aq., and the H3BO3 solution added to the final concentration of 0.25 mol L-1. The degreased glass substrates were suspended ver-tically into the parent solution, and reacted for 24 hours at 30 C.  3. CONTRIBUTION OF FLUORINE SCAVENGER FOR EQUILIBRIUM REACTION IN THE LPD PROCESS  Fig. 1 shows representative 19F NMR spectra of the reaction time dependence of the LPD reaction solution at the initial concentrations of 0.1 mol L-1 (NH4)2TiF6 and 0.2 mol L-1 H3BO3. From the spectrum of (NH4)2TiF6 solution, only one signal due to TiF62- was observed, thus TiF62- anions were quite stable in water.  On the other hand, a quartet which intensity ratio was weird was observed at -149 ppm after 1 hour LPD reac-tion, and a doublet which was asymmetrical intensities was observed at -156 ppm after 6 hours LPD reaction, and these signals can be assigned to BF3(OH)- and BF4-, respectively[5]. Free F- anions which were produced by the hydrolysis reaction of TiF62- were completely scav-enged by H3BO3, hence the signal due to free F- ions were not detected in the LPD reaction solution at each reaction time. The signals which derived from BF(OH)3-  M. MIZUHATA, H. IKUTA, Y. OKUMURA, H. MAKI PROC. NAP 2, 01NTF36 (2013)   01NTF36-2 and BF2(OH)2- could not be observed because the ligand exchange of these species is much faster than NMR time scale. In order to quantitatively clarify about the deposi-tion mechanism of titanium oxide thin films by the LPD process, the concentrations of the dissolving spe-cies in the LPD reaction solutions were determined by the comparing with the integrated intensity values of 19F NMR signals of external reference. An NMR is a powerful tool for not only determination of the dissolv-ing species but also their quantitative analysis because the integrated intensity is directly proportional to the number of resonant nuclei. Fig. 2 shows the time de-pendence of the concentrations of the dissolving species in the LPD reaction solutions. The relationships be-tween the concentrations of the reactant (TiF62-) and the products (BF3(OH)- and BF4-) indicated that the most rapid reaction occurred when the initial concen-tration of (NH4)2TiF6 was 0.025 mol L-1, and the ag-glomeration of particles as the precursor of a hazy TiO2 film was deposited. It is noteworthy that contrary to expectations the concentration of BF3(OH)- was higher than that of BF4- during whole reaction time, thus, a boron molecule will scavenge not four F- anions but three F- anions. Since the 19F NMR signals due to only TiF62-, BF3(OH)-, and BF4- species were observed, if TiF62- ions released all F- ions by the hydrolysis reac-tion as eq. (1), the following relationship will be estab-lished.   [TiF62-]con  6 = [BF3(OH)-]pro  3 + [BF4-]pro  4 (4)  where [TiF62-]con represents the concentration of TiF62- consumed by LPD reaction, [BF3(OH)-]pro and [BF4-]pro represent the concentrations of BF3(OH)- and BF4- pro-duced by F- consuming reaction, respectively. However, the concentration of F- which was released from TiF62- is much higher than that of F- which was scavenged by H3BO3 in all concentration conditions. This result sug-gests that TiF62- do not release all F- ions, namely, the existence of hydrolysis intermediate species (TiFx(OH)y(H2O)6-x-y(4-x-y)) which could not be detected by 19F NMR because of the rapid ligand exchange in the LPD reaction solutions. The complicated equilibrium behaviour of these various intermediate species in the LPD reaction solutions will affect the chemical compo-sition, the crystal structures, and the amount of yields of the metal oxide thin films.  4. SYNTHESIS MECHANISM OF CHROME (III) OXIDE THIN FILMS IN THE LPD PROCESS  Chrome (III) oxide which is the 3d transition metal oxide has many applications in a catalytic chemistry, a photolithography process and an electrode material. We also investigated the optimization of the synthesis condi-tion of the Chrome (III) oxide thin film. Since the solubili-ty product of Cr(OH)3 is 6.3×10-31, it can be expected that Cr(OH)3 which is precursor of the chrome (III) oxide thin film  precipitates in pH  4.6 at [Cr3+]  7.5 mmol L – 1.  The NH3 concentration dependence of Cr3+-HF and Cr3+-HNO3 mixture solutions as the pH of the LPD par-ent solutions is shown in Fig. 3. The Cr(OH)3 precipitat-ed in pH  4.6 as expected from the solubility product in the Cr3+-HNO3 solutions, on the other hand, in the case of the Cr3+-HF solution, the Cr(OH)3 precipitated in pH > 6.1 against the expectation. This indicates that F- anions which coordinates to Cr3+ inhibits the formation of Cr(OH)3. Hence, it can be expected that the chrome (III) oxide thin film is synthesized by the LPD process   Fig. 1 – 19F NMR spectra of 0.1 mol L-1 (NH4)2TiF6 aq. and reaction time dependence of LPD reaction solution. (NH4)2TiF6 aq : 0.1 mol L-1. H3BO3 aq : 0.2 mol L-1.  Fig. 2 – Reaction time dependence of the concentration of the dissolving species in LPD reaction solutions. (NH4)2TiF6 aq. : (a) 0.025 mol L-1, (b) 0.10 mol L-1, (c) 0.20 mol L-1. H3BO3 aq. : 0.20 mol L-1. ●: TiF62-, ■: BF3(OH)-, ▲: BF4- (a) (b) (c)  EQUILIBRIUM BEHAVIOR FOR TRANSITION METAL… PROC. NAP 2, 01NTF36 (2013)   01NTF36-3 when the hydrolysis of Cr3+ is inhibited by the coordina-tion of F- anions. That is to say, the addition of H3BO3 as a fluorine scavenger in condition that fluorine inhibits the hydrolysis of Cr3+ causes to slow desorption from Cr3+ of fluorine, and the LPD reaction proceeds and the chrome (III) oxide thin film will be deposited.  Fig. 4 shows the NH3 concentration dependence of the deposition amounts of chromium on the glass sub-strates by the LPD reaction and the initial and final pHs of the LPD reaction solutions. The depositions of chrome (III) oxide thin film were observed when the hydrolysis reaction of the complex was inhibited by the coordination of F-, i.e. pH > 4.6. Therefore, it was revealed that the optimization of the LPD reaction can be carried out by the controlling of the concentrations of reaction species and pH. The formation of the thin film of ca. 100 nm in   membrane thickness was confirmed by the surface ob-servation with SEM, and it was confirmed that the com position was amorphous Cr2O3 with XRD and Raman spectrometry. Furthermore, the syntheses of the metal oxide thin films of Ti, V, Mn, Fe, Co, and Cu were ac-complished by the appropriate control of the pH and the concentration of the reactive species in this study.  AKNOWLEDGEMENTS  A part of this study was supported by the Energy and Environment Technologies Development Projects “Development of an Electric Energy Storage System for Grid-connection with New Energy Resources” support-ed by Kawasaki Heavy Industries (KHI) Ltd. and New Energy and Industrial Technology Organization (NE-DO), and partially Grant-in-Aid for Scientific Research (B) (No. 22350094) by JSPS, Japan.   REFERENCES  1. S. Deki, Y. Aoi, O. Hiroi, A. Kajinami, Chem. Lett. 25, 433 (1996). 2. S. Deki, Y. Aoi, Y. Miyake, A. Gotoh, A. Kajinami, Mater. Res. Bull. 31, 1399 (1996). 3. S. Deki, Y. Aoi, J. Okibe, H. Yanagimoto, A. Kajinami, M. Mizuhata, J. Mater. Chem., 7, 1769 (1997) 4. S. Deki, S. Iizuka, K. Akamatsu, M. Mizuhata, A. Kajinami, J. Am. Ceram. Soc. 88, 731 (2005). 5. R.E. Mesmer, A.C. Rutenberg, Inorg. Chem. 12, 699 (1973).  00.511.522.51234560 40 80 120Cr / mmol m-2pH of reaction solution / - [NH4OH] / mmol L-1pH 4.6ini.fin.Fig. 4 – Various deposition amounts of Cr on substrates by LPD reaction with various [NH3]. [Cr] = 7.5 mmol L-1, [HF] = 150 mmol L-1, [NH3] = 0 – 130 mmol L-1, reaction temp.: 30ºC and reaction time: 24 h. 135790 50 100 150 200pH of parent solution / -[NH4OH] / mmol L-1pH = 4.6HFHNO3precipitationFig. 3 – Various pH of Cr3+-HF and -HNO3 aq. with various [NH3]. [Cr]  7.5 mmol L-1, [HF, HNO3]  150 mmol L-1, [NH3]  0 – 240 mmol L-1, dash line: dissolution, solid line: precipitation.  

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  
NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 2 No 1, 01NTF36(3pp) (2013) 
 
 
2304-1862/2013/2(1)01NTF36(3) 01NTF36-1  2013 Sumy State University 
Equilibrium Behavior for Transition Metal Ionic Species 
in Liquid Phase Deposition Reaction 
 
Minoru Mizuhata*, Hirotaka Ikuta, Yuzo Okumura, Hideshi Maki 
 
Department of Chemical Science and Engineering, Graduate School of Engineering, 
Kobe University, 1-1 Rokkodai-cho, Nada, Kobe, 657-8501 Japan 
 
(Received 10 June 2013; published online 03 September 2013) 
 
We tried to clarify to the deposition mechanism by applying the 11B and 19F NMR analyses to the 
LPD reaction solutions for the preparing titanium oxide films with various reaction conditions. Moreover, 
the optimum conditions of the syntheses of 3d transition metal oxide thin films were investigated by con-
trolling pH and the concentration of reacting species.  In the reaction of TiO2 deposition, TiF62- do not re-
lease all F- ions, namely, the existence of hydrolysis intermediate species (TiFx(OH)y(H2O)6-x-y(4-x-y)) 
which could not be detected by 19F NMR because of the rapid ligand exchange in the LPD reaction solu-
tions.  In the reaction of Cr2O3 deposition, the optimization of the LPD reaction can be carried out by the 
controlling of the concentrations of reaction species and pH. 
 
Keywords: Liquid Phase Deposition, Titanium Oxide, Chromium Oxide, Transition Metal Oxide 
 
  PACS number: 73.90._f 
 
 
                                                          
* mizuhata@kobe-u.ac.jp 
1. INTRODUCTION 
 
Metal oxide thin films have been widely applied as 
inorganic functional materials due to their electrical, 
optical, and magnetic properties. Recently, a novel wet 
process called Liquid Phase Deposition (LPD) method 
has attracted much attention. The LPD reaction spon-
taneously proceeds at ambient condition in a balance of 
two equilibrium reactions, which are principally de-
scribed as follows: the hydrolysis equilibrium (ligand-
exchange) reaction of metal fluoride complex species 
(eq. 1) and the F– consumption reaction with boric acid 
or aluminum ion as an F– scavenger (eq. 2 or 3)[1]. 
 
 MFx(x-2n)- + H2O ↔ MOn + xF– + 2nH+ (1) 
 
(M; e.g. Ti, Fe, Cu, Zr, Sn, W, Mo, V, Zr, Nb, Ni)  
 
 H3BO3 + 4HF → BF4– + H3O+ + 2H2O (2) 
 
 Al3+ + 6HF → H3AlF6 + 3/2H2  (3) 
 
Deki et al. have adapted LPD method to the fabrica-
tion of various kinds of films, such as titanium oxide, 
vanadium oxide, iron oxy-hydroxide and multi compo-
nent metal oxide films [2-4]. However, a small amount 
of fluorine is incorporated into the synthesized thin 
film and the essence of the deposition mechanism is 
still unclear. The clarification of the LPD reaction 
mechanism is indispensable to optimization, the high 
yield synthesis, and the physical properties improve-
ment of the thin film synthesis condition. In this work, 
we tried to clarify to the deposition mechanism by ap-
plying the 11B and 19F NMR analyses to the LPD reac-
tion solutions for the preparing titanium oxide films 
with various reaction conditions. Moreover, the opti-
mum conditions of the syntheses of 3d transition metal 
oxide thin films were investigated by controlling pH 
and the concentration of reacting species. 
 
2. EXPERIMENTAL 
 
The (NH4)2TiF6 concentrations of the parent solu-
tions for the syntheses of TiO2 thin films  were 0.025, 
0.1 and 0.2 mol L-1, and the H3BO3 concentration was 
fixed at 0.2 mol L-1. The degreased glass substrates 
were suspended vertically into the parent solution, and 
reacted at 30 C. The 19F NMR spectra were obtained by 
a Varian INOVA 400 NMR spectrometer. For the syn-
theses of Cr2O3 thin films, the Cr(NO3)3 and the HF 
concentrations of the parent solutions were 0.05 mol L-1 
and 0.15 mol L-1, respectively. The pH of the parent 
solutions were controlled by NH3 aq., and the H3BO3 
solution added to the final concentration of 0.25 mol L-
1. The degreased glass substrates were suspended ver-
tically into the parent solution, and reacted for 24 
hours at 30 C. 
 
3. CONTRIBUTION OF FLUORINE SCAVENGER 
FOR EQUILIBRIUM REACTION IN THE LPD 
PROCESS 
 
Fig. 1 shows representative 19F NMR spectra of the 
reaction time dependence of the LPD reaction solution 
at the initial concentrations of 0.1 mol L-1 (NH4)2TiF6 
and 0.2 mol L-1 H3BO3. From the spectrum of 
(NH4)2TiF6 solution, only one signal due to TiF62- was 
observed, thus TiF62- anions were quite stable in water.  
On the other hand, a quartet which intensity ratio was 
weird was observed at -149 ppm after 1 hour LPD reac-
tion, and a doublet which was asymmetrical intensities 
was observed at -156 ppm after 6 hours LPD reaction, 
and these signals can be assigned to BF3(OH)- and BF4-, 
respectively[5]. Free F- anions which were produced by 
the hydrolysis reaction of TiF62- were completely scav-
enged by H3BO3, hence the signal due to free F- ions 
were not detected in the LPD reaction solution at each 
reaction time. The signals which derived from BF(OH)3- 
 M. MIZUHATA, H. IKUTA, Y. OKUMURA, H. MAKI PROC. NAP 2, 01NTF36 (2013) 
 
 
01NTF36-2 
and BF2(OH)2- could not be observed because the ligand 
exchange of these species is much faster than NMR 
time scale. 
In order to quantitatively clarify about the deposi-
tion mechanism of titanium oxide thin films by the 
LPD process, the concentrations of the dissolving spe-
cies in the LPD reaction solutions were determined by 
the comparing with the integrated intensity values of 
19F NMR signals of external reference. An NMR is a 
powerful tool for not only determination of the dissolv-
ing species but also their quantitative analysis because 
the integrated intensity is directly proportional to the 
number of resonant nuclei. Fig. 2 shows the time de-
pendence of the concentrations of the dissolving species 
in the LPD reaction solutions. The relationships be-
tween the concentrations of the reactant (TiF62-) and 
the products (BF3(OH)- and BF4-) indicated that the 
most rapid reaction occurred when the initial concen-
tration of (NH4)2TiF6 was 0.025 mol L-1, and the ag-
glomeration of particles as the precursor of a hazy TiO2 
film was deposited. It is noteworthy that contrary to 
expectations the concentration of BF3(OH)- was higher 
than that of BF4- during whole reaction time, thus, a 
boron molecule will scavenge not four F- anions but 
three F- anions. Since the 19F NMR signals due to only 
TiF62-, BF3(OH)-, and BF4- species were observed, if 
TiF62- ions released all F- ions by the hydrolysis reac-
tion as eq. (1), the following relationship will be estab-
lished. 
 
 [TiF62-]con  6 = [BF3(OH)-]pro  3 + [BF4-]pro  4 (4) 
 
where [TiF62-]con represents the concentration of TiF62- 
consumed by LPD reaction, [BF3(OH)-]pro and [BF4-]pro 
represent the concentrations of BF3(OH)- and BF4- pro-
duced by F- consuming reaction, respectively. However, 
the concentration of F- which was released from TiF62- 
is much higher than that of F- which was scavenged by 
H3BO3 in all concentration conditions. This result sug-
gests that TiF62- do not release all F- ions, namely, the 
existence of hydrolysis intermediate species 
(TiFx(OH)y(H2O)6-x-y(4-x-y)) which could not be detected by 
19F NMR because of the rapid ligand exchange in the 
LPD reaction solutions. The complicated equilibrium 
behaviour of these various intermediate species in the 
LPD reaction solutions will affect the chemical compo-
sition, the crystal structures, and the amount of yields 
of the metal oxide thin films. 
 
4. SYNTHESIS MECHANISM OF CHROME (III) 
OXIDE THIN FILMS IN THE LPD PROCESS 
 
Chrome (III) oxide which is the 3d transition metal 
oxide has many applications in a catalytic chemistry, a 
photolithography process and an electrode material. We 
also investigated the optimization of the synthesis condi-
tion of the Chrome (III) oxide thin film. Since the solubili-
ty product of Cr(OH)3 is 6.3×10-31, it can be expected that 
Cr(OH)3 which is precursor of the chrome (III) oxide thin 
film  precipitates in pH  4.6 at [Cr3+]  7.5 mmol L – 1.  
The NH3 concentration dependence of Cr3+-HF and 
Cr3+-HNO3 mixture solutions as the pH of the LPD par-
ent solutions is shown in Fig. 3. The Cr(OH)3 precipitat-
ed in pH  4.6 as expected from the solubility product in 
the Cr3+-HNO3 solutions, on the other hand, in the case 
of the Cr3+-HF solution, the Cr(OH)3 precipitated in 
pH > 6.1 against the expectation. This indicates that F- 
anions which coordinates to Cr3+ inhibits the formation 
of Cr(OH)3. Hence, it can be expected that the chrome 
(III) oxide thin film is synthesized by the LPD process  
 
Fig. 1 – 19F NMR spectra of 0.1 mol L-1 (NH4)2TiF6 aq. and 
reaction time dependence of LPD reaction solution. 
(NH4)2TiF6 aq : 0.1 mol L-1. H3BO3 aq : 0.2 mol L-1.  
Fig. 2 – Reaction time dependence of the concentration of the dissolving species in LPD reaction solutions. (NH4)2TiF6 
aq. : (a) 0.025 mol L-1, (b) 0.10 mol L-1, (c) 0.20 mol L-1. H3BO3 aq. : 0.20 mol L-1. ●: TiF62-, ■: BF3(OH)-, ▲: BF4- 
(a) (b) (c) 
 EQUILIBRIUM BEHAVIOR FOR TRANSITION METAL… PROC. NAP 2, 01NTF36 (2013) 
 
 
01NTF36-3 
when the hydrolysis of Cr3+ is inhibited by the coordina-
tion of F- anions. That is to say, the addition of H3BO3 as 
a fluorine scavenger in condition that fluorine inhibits 
the hydrolysis of Cr3+ causes to slow desorption from 
Cr3+ of fluorine, and the LPD reaction proceeds and the 
chrome (III) oxide thin film will be deposited.  
Fig. 4 shows the NH3 concentration dependence of 
the deposition amounts of chromium on the glass sub-
strates by the LPD reaction and the initial and final pHs 
of the LPD reaction solutions. The depositions of chrome 
(III) oxide thin film were observed when the hydrolysis 
reaction of the complex was inhibited by the coordination 
of F-, i.e. pH > 4.6. Therefore, it was revealed that the 
optimization of the LPD reaction can be carried out by 
the controlling of the concentrations of reaction species 
and pH. The formation of the thin film of ca. 100 nm in  
 
membrane thickness was confirmed by the surface ob-
servation with SEM, and it was confirmed that the com 
position was amorphous Cr2O3 with XRD and Raman 
spectrometry. Furthermore, the syntheses of the metal 
oxide thin films of Ti, V, Mn, Fe, Co, and Cu were ac-
complished by the appropriate control of the pH and the 
concentration of the reactive species in this study. 
 
AKNOWLEDGEMENTS 
 
A part of this study was supported by the Energy 
and Environment Technologies Development Projects 
“Development of an Electric Energy Storage System for 
Grid-connection with New Energy Resources” support-
ed by Kawasaki Heavy Industries (KHI) Ltd. and New 
Energy and Industrial Technology Organization (NE-
DO), and partially Grant-in-Aid for Scientific Research 
(B) (No. 22350094) by JSPS, Japan. 
 
 
REFERENCES 
 
1. S. Deki, Y. Aoi, O. Hiroi, A. Kajinami, Chem. Lett. 25, 433 
(1996). 
2. S. Deki, Y. Aoi, Y. Miyake, A. Gotoh, A. Kajinami, Mater. 
Res. Bull. 31, 1399 (1996). 
3. S. Deki, Y. Aoi, J. Okibe, H. Yanagimoto, A. Kajinami, 
M. Mizuhata, J. Mater. Chem., 7, 1769 (1997) 
4. S. Deki, S. Iizuka, K. Akamatsu, M. Mizuhata, 
A. Kajinami, J. Am. Ceram. Soc. 88, 731 (2005). 
5. R.E. Mesmer, A.C. Rutenberg, Inorg. Chem. 12, 699 (1973). 
 
0
0.5
1
1.5
2
2.5
1
2
3
4
5
6
0 40 80 120
C
r 
/ 
m
m
o
l 
m
-2
p
H
 o
f re
a
c
tio
n
 s
o
lu
tio
n
 / - 
[NH
4
OH] / mmol L-1
pH 4.6
ini.
fin.
Fig. 4 – Various deposition amounts of Cr on 
substrates by LPD reaction with various [NH3]. [Cr] = 
7.5 mmol L-1, [HF] = 150 mmol L-1, [NH3] = 0 – 130 
mmol L-1, reaction temp.: 30ºC and reaction time: 24 h. 
1
3
5
7
9
0 50 100 150 200
p
H
 o
f 
p
a
re
n
t 
s
o
lu
ti
o
n
 /
 -
[NH
4
OH] / mmol L-1
pH = 4.6
HF
HNO
3
precipitation
Fig. 3 – Various pH of Cr3+-HF and -HNO3 aq. with various 
[NH3]. [Cr]  7.5 mmol L-1, [HF, HNO3]  150 mmol L-1, 
[NH3]  0 – 240 mmol L-1, dash line: dissolution, solid line: 
precipitation. 
 


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Equilibrium Behavior for Transition Metal Ionic Species in Liquid Phase Deposition Reaction

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