These types of request use the syntax of ISO 8601 dates.

Examples extracted from the Solr documentation: http://wiki.apache.org/solr/SolrQuerySyntax

timestamp:[* TO NOW]

createdate:[1976-03-06T23:59:59.999Z TO *]

createdate:[1995-12-31T23:59:59.999Z TO 2007-03-06T00:00:00Z]

pubdate:[NOW-1YEAR/DAY TO NOW/DAY+1DAY]

note: /DAY is rounded up to the start of today

createdate:[1976-03-06T23:59:59.999Z TO 1976-03-06T23:59:59.999Z+1YEAR]

createdate:[1976-03-06T23:59:59.999Z/YEAR TO 1976-03-06T23:59:59.999Z]

For example: the last 24hr: [NOW-1DAY TO NOW]

http://www.idref.fr/Sru/Solr?wt=xml&version=2.2&start=&rows=30&indent=on&fl=ppn_z,dateetat_dt&q=dateetat_dt :[NOW-1DAY%20TO%20NOW]