ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 12, pp. 1913!1918. + Pleiades Publishing, Inc., 2006.
Original Russian Text + V.Yu. Dolmatov, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 12, pp. 1937!1941.
AND INDUSTRIAL INORGANIC CHEMISTRY
Development of a Rational Technology for Synthesis
of High-Quality Detonation Nanodiamonds
V. Yu. Dolmatov
Tekhnolog FGUP SKTB, St. Petersburg, Russia
Received February 9, 2005; in final form, June 2006
Abstract-Concepts concerning the structure of detonation nanodiamonds were generalized on the basis of
data reported in previous publications. The pH value of the nanodiamonds in an aqueous suspension was
determined. The mechanism of the longest stage, washing of nanodiamonds with water to remove excess
acidity, was considered. A novel method for substantially improving the quality of nanodiamonds and
the stability of aqueous suspensions of nanodiamonds was suggested.
The task of achieving a high purity of detonation
nanodiamonds and preparing stable nanosize suspen-
sions is a key issue for successful application of nano-
diamonds in various areas of science and technology.
However, due attention has not been given to this
question because of the complexity of these problems.
This study is devoted to generalization of concepts
about the structure of nanodiamonds and to practical
solution of the above problems.
Detonation nanodiamonds (average size 43 6 nm)
are exceedingly complex objects having, at least,
a three-layer structure . Each particle (cluster)
contained in aggregates is a set of constituent ele-
(1) A core composed of carbon atoms (sp
bridized) bound into a cubic crystal structure charac-
teristic of diamond includes 703 90% of carbon atoms
and has, according to X-ray data, a size of 403 60 A;
the core contains 2.532.8 wt % nitrogen as substitu-
tion atoms .
(2) An intermediate carbon sheath of thickness
4310 A, which envelops the core, is composed of
X-ray-amorphous carbon structures, and may contain
10330% of carbon atoms of the cluster . The sheath
composed of sp
-hybridized carbon is inhomogeneous.
It is believed  that the inner layer of this sheath,
immediately adjacent to the diamond core, is com-
posed of continuous layers of onion-like carbon.
Above the inner layer are situated, within the same
sheath, fragmented graphite-like monolayers. This
amorphous carbon sheath has a porous structure,
contains numerous defects and discontinuous regions
of structural carbon formations, and may include
a minor amount of heteroatoms incorporated into
the sheath in the course of detonation synthesis and
(3) Surface layer containing, in addition to carbon
atoms, also other heteroatoms forming a broad spec-
trum of widely diverse functional groups. The amount
of heteroatoms may be as large as 10% relative to
the total mass of a particle, and oxygen may constitute
their larger part . Hydrogen contained in functional
groups and nitrogen rather uniformly distributed over
all layers of nanodiamonds are revealed in minor
amounts. The major place is occupied by oxygen-con-
taining groups (hydroxy, carboxyl, ketone, lactone,
In view of the fact that the core and its intermedi-
ate sheath are nearly wholly composed of carbon, all
the heteroatoms (except nitrogen) are concentrated
in the surface layer and their content in the surface
layer is about 50%, i.e. , nanodiamond particles
are not a purely carbon material. Moreover, carbon
itself is present in the product simultaneously in sev-
eral modifications, and only one of these corresponds
to the structure of diamond.
The structure and quantitative characteristics of
the core and intermediate carbon sheath of nanodia-
monds are formed in the course of detonation syn-
thesis [3, 7]. The outer sheath determines the relation-
ship between the nanodiamond cluster and the envi-
ronment. It is this sheath that forms the interface and